U.S. patent number 6,696,914 [Application Number 09/914,409] was granted by the patent office on 2004-02-24 for electrical fuse for rotary current generator with rectifier.
This patent grant is currently assigned to Robert Bosch GmbH. Invention is credited to Walter Csicser, Martin Haupt, Holger Haussmann, Karl-Otto Heinz, Herbert Labitzke, Klaus-Uwe Mittelstaedt, Holger Scholzen, Henning Stilke.
United States Patent |
6,696,914 |
Haupt , et al. |
February 24, 2004 |
Electrical fuse for rotary current generator with rectifier
Abstract
The invention relates to an electrical fuse for rotary current
generators, having a rectifier assembly (14) for supplying a DC
network, in particular in motor vehicles. To achieve simple,
cost-effective and rapid-response fuse performance in the event of
an overload, it is provided that a fuse element (21) be disposed in
a line strand, carrying all the generator current, between the
rectifier assembly (14) and a DC connection terminal (22) of the
generator.
Inventors: |
Haupt; Martin (Cowbridge,
GB), Labitzke; Herbert (Markgroeningen,
DE), Csicser; Walter (Schwieberdingen, DE),
Mittelstaedt; Klaus-Uwe (Weissach, DE), Scholzen;
Holger (Schwieberdingen, DE), Heinz; Karl-Otto
(Remseck, DE), Haussmann; Holger (Metzingen,
DE), Stilke; Henning (Rotenburg/Wuemme,
DE) |
Assignee: |
Robert Bosch GmbH (Stuttgart,
DE)
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Family
ID: |
7934898 |
Appl.
No.: |
09/914,409 |
Filed: |
January 25, 2002 |
PCT
Filed: |
December 21, 2000 |
PCT No.: |
PCT/DE00/04568 |
PCT
Pub. No.: |
WO01/50577 |
PCT
Pub. Date: |
July 12, 2001 |
Foreign Application Priority Data
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Dec 29, 1999 [DE] |
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199 63 622 |
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Current U.S.
Class: |
337/295; 337/187;
337/227; 337/290; 361/20; 361/837; 439/890; 439/893 |
Current CPC
Class: |
H01H
85/0241 (20130101); H01H 85/044 (20130101); H02K
11/046 (20130101); H01H 85/47 (20130101); H01H
2085/0283 (20130101) |
Current International
Class: |
H01H
85/02 (20060101); H01H 85/044 (20060101); H01H
85/00 (20060101); H02K 11/04 (20060101); H01H
85/47 (20060101); H01H 085/08 (); H01H 085/20 ();
H01R 013/68 () |
Field of
Search: |
;337/159,186,187,227,290,295 ;439/621,622,890,893 ;361/837,20 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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30 01 522 |
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Jul 1981 |
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DE |
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19741830 |
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Mar 1999 |
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DE |
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19936279 |
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Feb 2000 |
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DE |
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2358742 |
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Mar 1978 |
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FR |
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2732823 |
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Oct 1996 |
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FR |
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1417913 |
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Dec 1975 |
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GB |
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11040041 |
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Feb 1999 |
|
JP |
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2001273848 |
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Oct 2001 |
|
JP |
|
2002136076 |
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May 2002 |
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JP |
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WO 8801790 |
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Mar 1988 |
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WO |
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Primary Examiner: Vortman; Anatoly
Attorney, Agent or Firm: Striker; Michael J.
Claims
What is claimed is:
1. An electrical fuse (21, 40) for rotary current generators,
having a rectifier assembly (14) for supplying a dc network, in
particular in motor vehicles, characterized in that the fuse is
disposed, in the form of a fuse element (21, 40), in a line segment
carrying all the generator current, between the rectifier assembly
(14) and a generator connection terminal (22, 25) of the generator,
wherein the fuse element (21, 40) is disposed between a heat sink
(20), forming the positive pole, of the rectifier assembly (14) and
a positive connection bolt (25) of the generator, forming the
generator connection terminal (22), and the positive connection
bolt (25) is secured in insulated fashion and detachably on the
positive heat sink (20) in a hole (33) in the positive heat sink
(20).
2. The electrical fuse of claim 1, wherein the fuse element (21),
together with an insulator part (26) that embraces the head (27) of
the positive connection bolt (25), is slipped onto the positive
connection bolt (25) and put into electrical contact with it on the
face end (27a) of the head (27).
3. The electrical fuse of claim 2, wherein the positive connection
bolt (25), insulator part (26) and fuse element (21) form a
prefabricated component unit (24), in that the fuse element (21) is
galvanically connected, preferably welded, by one terminal (29), to
the connection bold head (27), on the face end (27a) thereof.
4. The electrical fuse of claim 3, wherein with its other terminal
(30), the fuse element (21) is embodied annularly and is placed on
a collar (26a), embracing the connection bolt (25), of the
insulator part (26), so that this terminal, on its top side, is put
into electrical contact with the positive heat sink (20) by
pressure.
5. The electrical fuse of claim 4, wherein the fuse element (21) is
a stamped metal part, which between its two terminals (29, 30) has
a portion (31) of narrowed cross section, embraced laterally on the
head (27) of the positive connection bolt (25) by the insulator
part (26), which portion melts away in the event of an
overload.
6. The electrical fuse of claim 2, wherein an insulating ring (34)
is placed on the connection bolt (25) on the positive heat sink
(25), in order to insulated the positive heat sink (20) from a
protective cap (32) that is secured in a manner known per se on the
connection bolt (25).
7. The electrical fuse of claim 1, wherein the positive connection
bolt (25) is embraced at its head region (27) by an insulator part
(41) and protrudes in insulated fashion through the hole (33) in
the positive heat sink, the fuse element (40) being placed on the
positive connection bold (25) in such a way that with its lower
terminal (29), it rests on the positive heat sink (20), and with
its upper terminal (30), it is put into electrical contact with the
positive connection bolt (25) by means of a nut (37).
8. The electrical fuse of claim 7, wherein the fuse element (40) is
embodied of an annular, diskilke insulating substrate body (43),
which on each of its two ends has a respective annular-disklike
terminal (29, 30), and a melting portion (31, 31a) of narrowed
cross section is moved laterally past the insulating substrate body
(43) between the two terminals (29, 30).
9. The electrical fuse of claim 8, wherein the melting portion
(31a) is guided around a platelike protrusion (43a), formed
laterally onto the insulating substrate body (43), that embraces
the melting portion (31a) on both sides.
10. The electrical fuse of claim 9, wherein the protrusion (43a) of
the insulating substrate body (43) is embraced and positionally
fixed on both sides by lugs (44) formed onto the positive heat sink
(20).
11. The electrical fuse of claim 8, wherein the two
annular-diskilke terminals (29, 30) of the fuse element (40)
embrace the insulating substrate body (43) on its outer edge, in
each case by means of angled tongues (44).
12. The electrical fuse of claim 7, wherein a contact disk (42)
slipped onto the positive connection bolt (45) rests on the upper
terminal (29) of the fuse element (40) and is firmly fastened,
together with the fuse element (40) and the positive heat sink
(20), on the positive connection bolt (25) by the nut (37).
13. The electrical fuse of claim 12, wherein a clamping disk (36)
injected into a fastening opening (38) of a protective cap (32) is
fastened between the contact disk (42) and the nut (37).
Description
The invention relates to an electrical fuse for rotary current
generators, having a rectifier assembly for supplying a DC network,
in particular in motor vehicles, as generically defined by the
preamble to the main claim.
PRIOR ART
In motor vehicles, to an increasing extent electrical devices are
being used to improve the comfort and safety of the motor vehicles.
For supplying these devices from the on-board electrical system of
the motor vehicles, in by far the most cases, rotary current
generators are used, which have a high power density and are thus
under severe thermal loads. A rectifier assembly is as a rule
integrated with the housing of the rotary current generators, so
that only the DC output of this assembly forms the connection
terminals of the generator, to which the connection cables of an
accumulator battery of the on-board vehicle electrical system are
connected. In the event of an overload or a short circuit at the
generator or the rectifier assembly, which not infrequently happens
in motor vehicles whenever a battery charging device is connected
to the discharging battery with the wrong polarity, not only can
the generator or the rectifier assembly be destroyed, but this can
also trigger still further damage to the vehicle.
To avoid these dangers, it is already known from German Patent DE
30 01 522 C2, to dispose fuse elements in the rectifier assembly,
between the connections of the positive and negative diodes of the
three rectifier bridges. The fuses, which because of production
variations have only very imprecise response values, are formed by
line portions bent in a loop from recesses in a printed circuit
board of the rectifier assembly; these loops melt open in the event
of an electrical overload and can be temporarily repaired again by
twisting the ends together. Since the terminals of the
thus-protected power diodes of the rectifier assembly are soldered
or welded to the printed circuit board, once a fuse has responded,
the entire rectifier assembly later has to be replaced, which is
expensive and time-consuming. Moreover, there is the risk that the
fuse that has responded will be only temporarily repaired or in
other words bypassed, without the rectifier assembly being replaced
at the next opportunity. In that case, the risk of destruction and
overheating increases quite considerably. If the response of a fuse
in one of the three rectifier bridges goes unrecognized, the two
intact rectifier bridges are then loaded all the more heavily, so
that finally they fail as well.
The object of the present invention is to accomplish protection of
the generator and the rectifier assembly from electrical overload
or short circuit as simply and reliably as possible.
ADVANTAGE OF THE INVENTION
The electrical fuse of the invention having the characteristic of
the body of claim 1 has the advantage over the prior art that when
the fuse responds, the generator along with the rectifier assembly
is shut off completely, making the response of the fuse clearly
apparent from the interruption in the charging process. A further
advantage is that if a battery charging device is connected with
the wrong polarity, it is no longer necessary--as it was until
now--for all three fuses in the three rectifier bridges to respond;
instead, from the response of one fuse, the generator is completely
disconnected from the on-board electrical system, thus averting the
risk of overheating.
Advantageous refinements and embodiments are attained from the
other characteristics recited in the dependent claims. For
instance, an especially expedient embodiment that is simple from a
production standpoint is obtained if the fuse element is disposed
between a heat sink, forming the positive pole, of the bridge
rectifier and a positive connection bolt of the generator. The
positive connection bolt is fastened in insulated and detachable
fashion in a hole of the positive heat sink.
For the sake of changing the fuse as easily as possible if the fuse
has responded, it is expedient to slip the fuse element, together
with an insulator part embracing the head of the positive
connection bolt, onto the positive connection bolt and to be put
into electrical contact with it on the face end of the head. For
the sake of the most reliable possible contacting, it is also
proposed that the positive connection bolt, insulator part and fuse
element form a prefabricated component unit, in that the fuse
element is galvanically connected, preferably welded, by one
terminal, to the connection bolt head, on the face end thereof. In
this case, the complete component unit is replaced after the fuse
has responded.
The most reliable and simple connection of the fuse element to the
positive heat sink is attained in that with its other terminal, the
fuse element is embodied annularly and is placed on a collar,
embracing the connection bolt, of the insulator part, and this
terminal, on its top side, is put into electrical contact with the
positive heat sink by pressure when the connection bolt is
tightened.
Very simple production of the fuse element can be achieved in that
the fuse element is a stamped metal part, which between its two
terminals has a portion of narrowed cross section, embraced
laterally on the head of the positive connection bolt by the
insulator part, which portion melts away in the event of an
overload.
To prevent a direct connection of the positive heat sink to the
positive connection bolt and thus to prevent bypassing of the fuse
element, an insulating disk is advantageously placed on the
positive connection bolt above the positive heat sink, in order to
insulate the heat sink from a protective cap secured in a manner
known per se to the connection bolt.
As alternative to the aforementioned replacement of the entire
component unit with the fuse element, the embodiment can
expediently also be designed in terms of its construction such that
only the fuse element has to be replaced after its response. In
that event, it is provided that the positive connection bolt is
embraced at its head region by an insulator part and protrudes in
insulated fashion through the hole in the positive heat sink, the
fuse element being placed on the positive connection bolt in such a
way that with its lower terminal, it rests on the positive heat
sink, and with its upper terminal, it is put into electrical
contact with the positive connection bolt by means of a nut.
Also in this respect, it is provided that the fuse element is
embodied of an annular, disklike insulating substrate body, which
on each of its two face ends has a respective annular-disklike
terminal, and a melting portion of narrowed cross section is moved
laterally past the insulating substrate body between the two
terminals.
For the sake of safety, to make it possible to fasten the portion
that melts away upon response of the fuse in a predetermined
position, secure against rotation and positionally securely, on the
positive connection bolt, this portion is guided around a platelike
protrusion, formed laterally onto the insulating substrate body,
that embraces the melting portion on both sides. In addition, this
protrusion is positionally fixed on both sides by lugs that are
formed onto the positive heat sink.
Since this fuse element can also be put on the market as a spare
part, the insulating substrate body must not fall out between the
two terminals of the fuse element before installation. To that end,
it is provided that the two annular-disklike terminals of the fuse
element embrace the insulating substrate body on its outer edge, in
each case by means of angled tongues.
DRAWING
Further details of the invention are described in further detail in
the two exemplary embodiments described below in conjunction with
the associated drawing.
Shown are:
FIG. 1, the circuit of the rotary current generator along with the
rectifier assembly and the fuse;
FIG. 2, as a first exemplary embodiment, the positive connection
bolt with the fuse as a prefabricated component unit, and
FIG. 3, a sectional view of the positive connection bolt with the
fuse, mounted on the positive heat sink;
FIG. 4, as the second exemplary embodiment, a cross section of the
rectifier assembly in the region of the positive connection
bolt;
FIG. 5, in a three-dimensional view, the fuse element seated on the
positive connection bolt in a manner secure against relative
rotation; and
FIG. 6, in fragmentary section, a variant of the second exemplary
embodiment of FIG. 4.
DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
In FIG. 1, the three phases 10 of a rotary current generator are
shown, which by one end are combined into a "Y" connection and by
their other end are connected to a respective diode bridge 11, 12
and 13 of a rectifier assembly 14. For interconnection of the three
phases 10 to the three diode bridges, there is a printed circuit
board 15, and each of the three diode bridges comprises one
negative diode 16 and positive diode 17 connected in series. The
negative diodes are press-fitted on the anode side into a negative
heat sink 18, and the anode terminals of the negative diodes 16 are
thus combined by means of the negative heat sink 18 to form a
negative terminal 19. The positive diodes 17 are press-fitted on
the cathode side into a positive heat sink 20. In this heat sink
20, the cathode terminals of the positive diodes 17 are combined
and connected via a fuse element 21 to a positive terminal 22 of
the rectifier assembly 14. The fuse element 21 is dimensioned such
that in order to protect the generator and the rectifier diodes 16,
17, it melts open if the allowable maximum direct current (DC) is
exceeded, and thus interrupts the current circuit on the generator
side. This can happen for instance in the event of incorrect
polarity when a battery charging device is connected.
FIG. 2 shows a prefabricated component unit 24 comprising a
positive connection bolt 25, an insulator part 26 shown in section,
and the fuse element 21. The positive connection bolt 25 forms a DC
connection terminal of the rotary current generator for the
positive connection cable of an accumulator in the on-board
electrical system of a motor vehicle. The insulator part 26 is
embodied such that it embraces the head 27 of the connection bolt
25. It is also provided with a collar 26a that embraces the shaft
25a. The fuse element 21 is slipped onto the positive connection
bolt 25 together with the insulator part 26 and put into electrical
contact with the head 27 on the face end 27a of the head, being
solidly welded by its lower terminal 29 to the face end 27a of the
head 27. With its upper terminal 30, it is embodied annularly and
is slipped onto the collar 26a of the insulator part 26. The fuse
element 21 is a stamped metal part, which between its two terminals
29, 30 has a portion 31 of narrowed cross section, embraced
laterally on the head 27 of the positive connection bolt 25 by the
insulator part 26, which portion melts away in the event of an
overload.
In FIG. 3, the positive connection bolt 25 is shown together with
the fuse element 21 and a protective cap 32, in cross section
mounted on the positive heat sink 20. The shaft 25a of the
connection bolt 25 protrudes in insulated fashion through a hole 33
in the positive heat sink 20, and the collar 26a of the insulator
part 26 protrudes into the hole 33, and furthermore the lower edge
33a of the hole 33 rests on the top side of the upper terminal 30
of the fuse element 21. The upper edge 33b of the hole 33 carries
an insulating ring 34, on which the protective cap 32, via a spring
disk 35, is braced with an injected clamping disk 36. The parts are
tightened against one another by a nut 37 placed on the positive
connection bolt 25. On the one hand, this pressure-contacts the
positive heat sink 20 to the upper terminal 30 of the fuse element
21, and on the other hand the positive heat sink is insulated by
the insulating ring 34 from the clamping disk 36 of the protective
cap 32 and thus also from the nut 37 and the connection bolt 25, to
prevent electrical bypassing of the fuse element 21.
Since the fuse is disposed, in the form of a fuse element 21, 40,
in a line segment that carries all the generator current between
the rectifier assembly 14 and a generator connection terminal 22,
25 of the generator, in the event of a response upon an overload
the fuse element 21 can easily be replaced. Since the positive
connection bolt 25 is secured detachably in the positive heat sink
22, in that event the entire component unit 24 of FIG. 2 can be
replaced.
In a second exemplary embodiment shown in FIGS. 4 and 5, the same
elements have the same reference numerals as in the first exemplary
embodiment. However, here the fuse element 40 is embodied such that
after response, it can be replaced by itself. Once again the
positive connection bolt 25 is embraced here in its head region 27
by an insulator part 41, which with a collar 41a protrudes into the
hole 33 of the positive heat sink 20. The fuse element 40 is placed
on the end of the positive connection bolt 25 that protrudes
through the hole 30 in such a way that it rests with its lower
terminal 29 on the positive heat sink 20. With its upper terminal
30, it is put into electrical contact with the positive connection
bolt 25 by means of the nut 37, in that first a contact disk 42
rests on the upper terminal 30. Onto this contact disk 42, the
protective cap 32 is now placed, with the clamping disk 36 injected
on the edge of the fastening opening 38, onto the positive
connection bolt 25. The protective cap 32, contact disk 42, fuse
element 40, heat sink 20 and insulator part 41 are finally
tightened firmly with the nut 37 placed on the thread of the
connection bolt 25.
The fuse element 40 here comprises an annular, disklike insulating
substrate body 43, with one annular-disklike terminal 29, 30 on
each of its two end faces, and with a melting portion 31a of
narrowed cross section, which is moved laterally past the
insulating substrate body 43 between the two terminals 29, 30 and
which melts away in the event of an overload. From the
three-dimensional view in FIG. 5, it can be seen that the melting
portion 31a is guided around a platelike protrusion 43a, formed
laterally onto the insulating substrate body 43, that embraces the
melting portion 31a on both sides. For positional fixation of the
fuse element 40 on the positive connection bolt 25, two lugs 44 are
formed onto the positive heat sink 20, which embrace the protrusion
43a of the insulating substrate body 43 on both sides and thus
embrace it in a manner secure against relative rotation. In
addition, the parts of the fuse element 40 are held together in
such a way that the two annular-disklike terminals 29 and 30 each
embrace the insulating substrate body 43 by means of angled tongues
45.
The positional fixation of the fuse element 40 has the advantage
that it can thus be assured that melting portion 31a will not come
into contact with metal components of the rectifier assembly and
thus bypass the fuse function. This also prevents the melting
portion 31a from coming into contact with temperature-sensitive
materials, such as the protective cap 32, and finally, the
positional fixation makes it possible to shift the rectifier
assembly with the fuse element 40 placed on it, without any change
occurring in its position. The spacing of the two lugs 44, which
can be embodied in any arbitrary cross-sectional shape, on the
positive heat sink 20 from one another should be selected such that
the fuse element 40 can be inserted with its protrusion 43a between
the two lugs 44 without restriction in the joining direction. This
positional fixation is possible without additional components,
since it can be recessed out of an existing mold for the positive
heat sink, using simple tools.
If the rectifier assembly and the protective cap 32 are embodied
such that the melting portion 31a of the fuse element 40 has an
adequate safety spacing from them anyway, then a positional
fixation of the fuse element can also be omitted. FIG. 6 shows an
alternative version for this purpose, in which the protrusion 43a
on the insulating substrate body 43 has been left out. Here, the
fuse element 40a is placed annularly onto the positive connection
bolt 25 and tightly fastened between the positive heat sink 20 and
the contact disk 42 by the nut 37. Its melting portion 31a can be
seated at any arbitrary point on the circumference of the
insulating substrate body 43.
* * * * *